Across:
8 Parents (Da + Ma = DAMA-), for example (e.g.), upset (= reversal indicator) (e.g. = -GE), (DAMAGE) by vandalism (DAMAGE),
9 Supported (APPROVED) Dubs from the start (‘Dubs’ from the start =-D) after (= position indicator) sanction (APPROVE-) (APPROVED),
10 Revolutionary (= reversal indicator) spotted (saw = WA-S) around yard (-Y-) (WAYS) giving directions (WAYS),
11 What happened when Lotto wasn’t won (ROLLED OVER) in Vienna? (Vienna ROLL-) Finished the champagne (finished the ‘champagnE’ = -E-) and English port! (Dover = -D OVER) (ROLLED OVER),
12 Concealed (SECRET) lie coming out of Leicester (‘lie’ coming out of ‘Leicester’ = cester = SECRET),
14 Improves (PERFECTS) and couldn’t be better (PERFECT-) at school (-S) (PERFECTS),
15 The really repellent section of Mein Kampf perhaps (A NASTY BIT OF WORK) produced by an unpleasant type locally (A NASTY BIT OF WORK),
18 Deploy speed reader perhaps (USE RADAR) to track when we can expect The Aviator (USE RADAR),
20 Gains (gains) ground (= anagram indicator) (gains = SA-ING) around Fourth of July (fourth of ‘julY’ = -Y-) (SAYING), in a manner of speaking (SAYING),
22 Prayer (PETITION-) from Spain (-E-) at the end of The War (end of the ‘waR’ = -R) (PETITIONER) appeals to authority (PETITIONER),
24 Both sides working like a charm (both sides ‘WOrking like a chaRM’ = WORM) and the birds love it (WORM),
25 See gross (see gross), crazy (= anagram indicator) (see gross = OGRESSES) big cannibals (man-eating female giants = OGRESSES),
26 English (E-) grain primarily (‘Grain’ primarily = -G-) found in beers (ales = -A-LES) (EAGLES) and in 23 down, for instance (EAGLES found in ‘nest’).
Down:
1 Head of department (manager) isn’t finished (r) (‘manager’ without ‘r’ = MANAGE) with master (MANAGE),
2 Falling out (spat = TAPS) over (= reversal indicator) watery types in the kitchen (TAPS),
3 12 across (‘secret’ = SECRET-) left (-L-) yard (-Y) (SECRETLY) on the sly (SECRETLY),
4 Taken in by manual labourer (taken in by retiring ‘manuaL LABourer’ = llab) turning up (= reversal indicator) (llab = BALL) for a fancy dance (BALL),
5 Emerge (APPEAR) with a (A-) starter of passion (starter of ‘Passion’ = -P-) fruit (-PEAR) (APPEAR),
6 Without interference, was allowed do whatever (GOT ONE’S WAY) to proceed (GO-) with sound (tone = -T ONE-) system – the first (‘System’ the first = -S) with most of 10 across (most of ‘ways’ = WAY) (GOT ONE’S WAY),
7 Sensitive type (DETECTOR) tends to be alarmist when Charlie registers? (DETECTOR alarm when Charlie/cocaine registers),
13 Arrested in (arrested in = RESTRAINED) riot (= anagram indicator) and put in chains (RESTRAINED),
14 The head of The House (PRIOR) or The Abbey (priory) briefly (y) (‘priory’ without ‘y’ = PRIOR),
16 23 down (‘nest’ = NEST) encourages (EGGS) (NEST EGGS) those reserved types who are put away (NEST EGGS),
17 Kept an eye on (OBSERVED) old (O-) backbencher, the first (backbencher the first = -B-) to dish out (-SERVE-) dirt on leader (‘Dirt’ on leader = -D) (OBSERVED),
19 Most in need of water (DRIEST) or wine that’s not sweet? (DRIEST wine),
21 New (N-) users (users) all over the place (= anagram indicator) (users = -URSES) (NURSES) working in the hospital (NURSES),
23 Local hotbed (NEST) of newspaper columnist’s extremes (‘NEwspaper columniST’ extremes = NEST),
24 Cost of employing one staff member (WAGE) to remove filth from white flag (remove ‘filth’ from ‘white flag’ = weag = WAGE).